Methods of Ballast Water Exchange
Sequential Method
A process by which a ballast tank is first emptied and then refilled with replacement ballast water to achieve at least 95% volumetric exchange. For this method each ballast tank should be discharged until suction is lost and stripping pumps or ejectors should be used if possible. Thus the process requires the removal of very large weights from the ship in a dynamic situation, and then their replacement.
Flow-through Method
A process by which replacement ballast water is pumped into a ballast tank, allowing water to flow through overflow or other arrangements. It is recommended by IMO Res.A.868(20) and established by most Port State Authorities that at least three times of the thank volume should be pumped through the tank. With it, normally an exchange of 95% of the ballast water may be achieved. A direct overflow via the airpipe head is not permitted as the long term load would lead to a failure of this component (respectively of the tank boundaries) and thus jeopardize the watertight integrity of the vessel.
Dilution Method
The dilution method is a process by which replacement ballast water is filled through the top or side of the ballast tank with simultaneous discharge from the bottom or opposite side at the same flow rate and maintaining constant level in the tanks throughout the ballast exchange operation. At least three times the tank volume is to be pumped through the tank. Commonly two ballast pumps are used simultaneously, whereby one is acting as filling pump and the other as suction pump. As it is essential to keep the filling level in the tanks constant, an exact control of the pumped volume of both pumps is to be ensured.
Other useful blogs
#merchant navy #shipping #mariner #sailors #india #singapore # tanker #cargo #enclosespace #gasdetection #safety #navigation #ecdis #alarms #bridge equipment #gprating #gp rating #maritimeinstitute #handingovertakingover #master #chiefmate #education @mariner #awareness #maritimeinstitute #russia #crew #telegramchannel #maritimestudies #indianmarititmeuniversity #imo @sailors #internationalmaritimeorganisation #philipines #china #emergencyshutdown #esd #cargo #portpapers #greece #usa @shipcrew @imo @maritime #mechanicalengineer #marineengineer #emergencygenerator #emergencyequipment
